Quantum dynamics in a camel-back potential of a dc SQUID

Abstract

We investigate the quantum dynamics of a quadratic-quartic anharmonic oscillator formed by a potential well between two potential barriers. We realize this novel potential shape with a superconducting circuit comprised of a loop interrupted by two Josephson junctions, with near-zero current bias and flux bias near half a flux quantum. We investigate escape out of the central well, which can occur via tunneling through either of the two barriers, and find good agreement with a generalized double-path macroscopic quantum tunneling theory. We also demonstrate that this system exhibits an "optimal line" in current and flux bias space along which the oscillator, which can be operated as a phase qubit, is insensitive to decoherence due to low-frequency current fluctuations.

References in corpus (7)

• Coherent Quantum Dynamics of a Superconducting Flux Qubit
• Observation of quantum oscillations between a Josephson phase qubit and a microscopic resonator using fast readout
• Coherent oscillations in a superconducting multi-level quantum system
• Temperature dependence of coherent oscillations in Josephson phase qubits
• Single-charge devices with ultrasmall Nb/AlOx/Nb trilayer Josephson junctions
• Multilevel effects in the Rabi oscillations of a Josephson phase qubit
• Nanosecond quantum state detection in a current biased dc SQUID

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